This invention relates to solenoids, and more particularly to the magnetic core constructions thereof. A characteristic of solenoids and magnets, which is often undesirable, is the unequal distribution of force over the working stroke, that is, the lack of a great force at the beginning of the working stroke, and the presence of excessive force at the end of the stroke. This is particularly noticeable where the stroke or movement of the core assemblage is relatively large. In the past various devices have been proposed and produced to improve this condition. Solenoids have been provided with dash-pots, clockworks and similar mechanical devices to smooth out the forces of the working stroke. In another direction, the core structures themselves have been altered and modified to level off the attractive force. A patent showing one such modified core structure is that issued to Werner, U.S. Pat. No. 1,699,866. Here the core laminations are joined by loose-fitting studs in the form of short, flat head screws which permit adjoining laminations to be either spaced apart of else contiguous with each other. While such an arrangement was operative for the desired purpose, it had drawbacks in that the screw threads required the laminations to be relatively thick, making for excessive eddy currents if alternating current is used for energizing the coil. Also, the stud or screw construction made for a costly product, considering component cost and assembly time.